The invention relates to valves for placement in liquid flow pipelines known as adjustable energy dissipating or head loss valves. The valves include an adjustable or movable plate and a fixed plate clamped within the valve body between an upstream and downstream flange in the pipe of various fixed diameters. A simple annular valve body permits clamping of the valve between pipe flanges with axially extending bolts. The downstream plate is fixed or stationary and perforated with a pattern of axial holes. The upstream plate is likewise perforated and is retained within the annular valve body for transverse sliding motion between a fully opened position where perforations in the fixed and mobile plates are aligned and fully closed position where the perforations within the fixed plate are blocked by the solid portions of the mobile plate.
An example of prior art loss of head valve is shown in U.S. Pat. No. 4,150,693 to Genevey et al. In this prior art valve, the mobile perforated plate is moved between the open and closed position with a manual hand wheel whose rotation meshes with a threaded rod that engages the mobile plate to open and close the valve. The mobile plate is guided in its movement by a stud opposite to the threaded rod, which slides in a slot.
A disadvantage of such prior art valves is that reverse flow or transient flow conditions acting on the mobile plate can dislodge it from its operating position causing damage, misalignment or disabling of the valve. In addition, the mobile plate may vibrate creating noise and potential wear or damage over the long term during bi-directional flow conditions.
It is an object of the invention to provide improved guidance and support for the mobile plate during operation to prevent misalignment, damage or noise during reversal of flow or bi-directional transient flow conditions.
Further objects of the invention will be apparent from review of the disclosure, drawings and description of the invention below.